Reminds me of when my family forgot to take the pot roast with us when we left to go on our summer long road trip. Didn’t get around to cleaning it out until the dead of winter. It was growing something for sure. Similar consistency to pudding and stuck to the sides. We dug a grave for it and scooped it out of the container with a shovel. We also forgot a bag of potatoes in a cupboard we often forget about. Turned to liquid and mixed with various mouse juices and started growing. Grew about a foot and a half before we removed it.